'Inst-455 1911 jig.pdf'. - Brownells

SAVE THESE INSTRUCTIONS IN YOUR BROWNELLS GUNSMITHS DATA RING BINDER
The Brownells/Marvel 1911 Auto Sear/Hammer Jig is designed to aid the
gunsmith in doing “match quality” trigger jobs on 1911 Auto pistols. The
combination jig and vise holds the sear and hammer in the proper relationship
to give the best, most consistent trigger work.
m WARNING m
Never attempt to disassemble or reassemble
a firearm unless you are absolutely certain that it is empty
and unloaded. Visually inspect the chamber, the magazine and firing
mechanism to be absolutely certain that no ammunition remains in the
firearm. Disassembly and reassembly should follow the manufacturer’s
instructions. If such instructions are not immediately available, contact
the manufacturer to see if they are available. If they are not available
at all, then you should consult other reference sources such as reference
books or persons with sufficient knowledge. If such alternative sources
are not available and you have a need to disassemble or reassemble the
firearm, you should proceed basing your procedures on common sense
and experience with similarly constructed firearms.
With regard to the use of these tools, the advice of Brownells Incorporated
is general. If there is any question as to a specific application
it would be best to seek out specific advice from other sources and not
solely rely on the general advice and warnings given.
HOW TO USE
Before starting any work, be sure to have all of the necessary components,
tools and accessories on hand.
Sequence of operations:
1) Fit a new trigger to the frame if an adjustable, overtravel-type trigger
is to be used.
2) Make sure the sear and hammer will fit into the frame if new parts are
being used.
3) Make certain the sear and hammer pins are not overly loose in the frame
and the sear and hammer are not excessively loose on their pins. Replace
the pins with new or oversize pins if necessary, fitting them per the
manufacturer’s instructions.
4) Prepare the hammer: (Note: It is absolutely vital that the hammer be
properly prepared. If the hooks are not cut at exactly 90° and perfectly
polished with the hook height set at .018" to .020", then it will be impossible
to obtain a consistent, reliable, clean, crisp trigger pull, no matter
how much work is done to the other components of the pistol. The best
components will be wasted if this work is not done properly!)
A) True the hammer hooks to 90° to the hammer flats if necessary, using
a Brownells Hammer Hook Squaring File. Do not cut the hooks
forward any more than is necessary to square them.
B) Reduce the hammer hook height to .018" to .020", keeping the top of
the hooks square to the hook face. (Figure 1)
C) Place the right lower end of the Jig in a bench vise. Note: A smooth
jawed bench vise is recommended, or if not available, smooth metallic
jaws will protect the Jig. (See illustration 1)
D) Using the 4mm/16mm screw, install the hammer in the hammer vise
portion of the Jig.
E) Place the hammer vise in Slot B and lightly tighten, using the Allen
head screw taken from Sear Jig’s insert.
F) Turn the stoning guide upside down and place on the top edge of the
Jig. (See illustration 2)
G) Use the height adjusting screw to move the hammer vise up until
the hammer flats are level and mate evenly with the lower side of
the inverted stoning guide.
H) Tighten the Allen head screw to hold the hammer vise in place.
I) Double check the hammer flats to ensure they are perfectly level,
then tighten the vise screw (3mm Allen wrench) to hold the hammer
in the correct position.
J) Turn the stoning guide over and position the legs of the stoning guide
in the slots in the jig body. Lightly stone the hammer hooks. We rec-
/MARVEL
1911 AUTO
SEAR/HAMMER
JIG
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#080-823-000
READ & FOLLOW THESE
INSTRUCTIONS
200 200 S. Front S. Front St. St. Montezuma, IA IA 50171 50171
800-741-0015 or 641-623-4000 or 641-623-4000 • www.brownells.com
• www.brownells.com
World’s World’s Largest Largest Supplier Supplier of of
Firearms Firearms Accessories Accessories and and Gunsmithing Gunsmithing Tools.
Tools.
ommend Brownells Hammer/Sear Stone Kit (#080-811-000) with its
6" x 1 ⁄2" x 1 ⁄2" stones for this operation. Use plenty of cutting oil with
the india stone, or water as a cutting agent for the ceramic stones in
this kit. You may wish to protect the sides of the stoning guide from
abrasion by use of a thin piece of steel shim stock between the stone
and the guide. Remove very little metal; just enough to correct the
angle or to polish the hook surfaces.
K) Inspect the hammer hooks for the correct angle. Refer to the illustrations
of hammer hook angles. (See illustration 3)
5) Prepare the Sear:
PRIMARY ANGLE
A) Firmly tighten the sear insert into Slot A on the Jig body. (Figure 2)
B) Place the sear on the sear post as shown in Figure 3 and lightly thread
the nut on the post. Do not overtighten.
C) Insert the spare hammer pin through the hammer and install the
hammer on the jig so the hammer hooks will line up with the sear
face. (Figure 3)
D) When the hammer and sear are correctly aligned as they would be
with the pistol cocked, tighten the nut firmly on top of the sear. Note:
overtightening the nut could cause the post to pull away from the
sear insert.
E) With the sear locked in place with the nut, remove the hammer and
hammer pin from the Jig. Remove the sear insert from Slot A and
place it in the Jig’s slot B.
F) Lightly tighten the insert in Slot B using the Allen head screw on the
back of the insert.
G) Use a layout fluid such as Dykem Steel Blue to lightly coat the sear’s
engaging surface.
H) Use the adjusting screw to position the insert so the sear engaging
surface is slightly above the level of the top of the Jig. Remember
that you will be removing very little metal from the sear...only about
.002" to .006".
I) Lock the insert in position and double check the height.
076-200-455 04007R © 2007 BROWNELLS, INC. MADE IN U.S.A.

J) Stone across the top of the sear until the stone is level with the top of
the Jig. (Figures 4 and 5)
K) Remove the sear insert from slot B and repeat steps A through J,
above. Use a finer grit stone than was used previously.
SECONDARY ANGLE
A) Remove the insert from slot B and place in slot C.
B) Adjust the sear so the sear’s point is slightly above the level of the
top of the Jig.
C) Tighten in place using the Allen head screw on the back of the insert.
D) Stone across the top of the sear point until the stone is level with the
top of the Jig. (Figure 6)
E) The finished sear should have approximately .020" engaging surface
remaining on the primary angle after the secondary angle has been
cut. (Figure 7)
F) Apply layout fluid (Dykem) to the sear. Check the sear’s engagement
with the hammer. We recommend using Brownells Trigger Adjustment
Pins on the outside of the frame to check engagement. (Figures
8 & 9)
6) If the engagement checks out okay, test-assemble the sear and hammer
in the frame and double check the engagement with all the related parts
assembled, including any replacement springs.
7) Perform any other work related to the action job.
A) This is the proper point in the work sequence to fit new thumb or
grip safeties.
B) Deburr and polish the mainspring housing hole for the mainspring.
Make sure the mainspring cap is polished and free to move within
the mainspring housing. If desired, replace the mainspring housing
with a lighter weight mainspring. (17 to 18lbs.)
C) Lightly polish the surfaces that contact the sear and disconnector.
Adjust the tension (bend) of the sear spring fingers.
D) Colt Series 80 guns: Polish the flat surfaces and mating surfaces of
the trigger bar lever, plunger and the firing pin plunger. Deburr the
surfaces of the frame and slide were the Series 80 parts touch them.
8) Reassemble the pistol and check all safeties for proper functioning.
NOTE: After doing action work on an autoloading pistol, the existing
safeties may need to be refitted. Be certain the thumb safety properly
blocks the sear and the grip safety blocks the trigger when in the “en-
gaged” position. In addition, the disconnector may need to be replaced or
refitted, especially if the slide has been tightened. If your pistol is a Colt
Series 80, be sure the firing pin lock safety features work properly to lock
the firing pin rearward until the trigger is pulled. You may have to refit
the existing parts or replace components of the firing pin lock system to
ensure when the trigger is pulled, the firing pin block plunger is cammed
out of engagement with the firing pin.
TROUBLE SHOOTING
A) Hammer Follows The Slide Forward:
1) Use layout fluid (Dykem) on the hammer hooks with the sear and
hammer in the frame to check if the sear is mating with only one hook.
If it is, correct by lightly stoning and then polishing the engaging surface.
Repeat until the sear bears evenly on both hammer hooks.
2) Check the hammer hooks for the correct height and angle.
3) Check the sear spring for correct shape and tension.
4) Replace the steel trigger with a lighter aluminum or composite trigger.
5) Review the instructions given for preparing the hammer and sear and
double check that you have followed them.
B) Heavy Trigger Pull or Creep:
1) With the gun unloaded, burnish the hammer hooks by applying pressure
to the back of the hammer in the full cock position while pulling
the trigger until it release.
2) It is possible the sear is too short from excessive stoning and/or tolerance
stacking of the frame’s set up with minimal metal removal.
4) See A), 1), 2) and 3) above.
C) Trigger Pull Too Light:
1) Decrease the sear’s secondary angle.
2) See A), 1), 2) and 3) above.
For additional information in action work on Colt 1911-type pistols, we
recommend Jerry Kuhnhausen’s book The Colt .45 Automatic, A Shop Manual.
Valuable information can also be found in .45 Auto Custom Touches, by
R. D. Nye. These books, as well as others by recognized authorities, can be
obtained from Brownells, Inc.
If you have any problems or need additional information, do not hesitate to
contact our technical staff.
MADE IN U.S.A. © 2007 BROWNELLS, INC 076-200-455 0407R

200 S. Front St. Montezuma, IA 50171
800-741-0015 or 641-623-4000 • www.brownells.com
World’s Largest Supplier of
Firearms Accessories and Gunsmithing Tools.
076-200-455 0407R © 2007 BROWNELLS, INC. MADE IN U.S.A.

200 S. Front St. Montezuma, IA 50171
800-741-0015 or 641-623-4000
www.brownells.com
World’s Largest Supplier of Firearms Accessories and Gunsmithing Tools.
MADE IN U.S.A. © 2007 BROWNELLS, INC 076-200-455 0407R